Private investors in agency MBS could lose $13 billion to $15 billion from a new government effort to help current Fannie Mae, Freddie Mac and FHA borrowers refinance, according to a new Congressional Budget Office staff working paper. The Obama administration is expected to announce a revved-up refinance program as part of a new strategy to strengthen economic growth. A “stylized” refinance program analyzed by the CBO would have a relatively small impact on the overall economy, the analysts said. The biggest impact would be on private MBS investors and the estimated 2.9 million households that would likely be brought into the...